The global Internet has become a mass media on par with radio and television. As a mass media, it has become an invaluable tool for companies wishing to advertise to potential customers and directly communicate with existing customers.
The main method of Internet advertising is through the use of advertisement-sponsored web sites. Web sites have been created for virtually every topic of human interest. To support the web site hosting expenses and the creation of new web site content, many web sites include advertising on their web sites.
One of the simplest features of the global Internet, electronic mail, is also one of its most powerful tools. With electronic mail (email), a user of the Internet can send a message to any other user on the Internet. With the advent of HTML formatted email messages, email can now contain images and hyperlinks to other resources. Additional files, such as programs or data, can also be enclosed within email. Thus, even though email is one of the oldest Internet applications, it remains one of the most important.